Is 818 a prime number?

It is possible to find out using mathematical methods whether a given integer is a prime number or not.

For 818, the answer is: No, 818 is not a prime number.

The list of all positive divisors (i.e., the list of all integers that divide 818) is as follows: 1, 2, 409, 818.

For 818 to be a prime number, it would have been required that 818 has only two divisors, i.e., itself and 1.

Find out more:

What is a prime number?

As a consequence:

818 is a multiple of 1
818 is a multiple of 2
818 is a multiple of 409

For 818 to be a prime number, it would have been required that 818 has only two divisors, i.e., itself and 1.

However, 818 is a semiprime (also called biprime or 2-almost-prime), because it is the product of a two non-necessarily distinct prime numbers. Indeed, 818 = 2 x 409, where 2 and 409 are both prime numbers.

Is 818 a deficient number?

Yes, 818 is a deficient number, that is to say 818 is a natural number that is strictly larger than the sum of its proper divisors, i.e., the divisors of 818 without 818 itself (that is 1 + 2 + 409 = 412).

Parity of 818

818 is an even number, because it is evenly divisible by 2: 818 / 2 = 409.

Find out more:

What is an even number?

Is 818 a perfect square number?

A number is a perfect square (or a square number) if its square root is an integer; that is to say, it is the product of an integer with itself. Here, the square root of 818 is about 28.601.

Thus, the square root of 818 is not an integer, and therefore 818 is not a square number.

What is the square number of 818?

The square of a number (here 818) is the result of the product of this number (818) by itself (i.e., 818 × 818); the square of 818 is sometimes called "raising 818 to the power 2", or "818 squared".

The square of 818 is 669 124 because 818 × 818 = 818² = 669 124.

As a consequence, 818 is the square root of 669 124.

Number of digits of 818

818 is a number with 3 digits.

What are the multiples of 818?

The multiples of 818 are all integers evenly divisible by 818, that is all numbers such that the remainder of the division by 818 is zero. There are infinitely many multiples of 818. The smallest multiples of 818 are:

0: indeed, 0 is divisible by any natural number, and it is thus a multiple of 818 too, since 0 × 818 = 0
818: indeed, 818 is a multiple of itself, since 818 is evenly divisible by 818 (we have 818 / 818 = 1, so the remainder of this division is indeed zero)
1 636: indeed, 1 636 = 818 × 2
2 454: indeed, 2 454 = 818 × 3
3 272: indeed, 3 272 = 818 × 4
4 090: indeed, 4 090 = 818 × 5
etc.

How to determine whether an integer is a prime number?

To determine the primality of a number, several algorithms can be used. The most naive technique is to test all divisors strictly smaller to the number of which we want to determine the primality (here 818). First, we can eliminate all even numbers greater than 2 (and hence 4, 6, 8…). Then, we can stop this check when we reach the square root of the number of which we want to determine the primality (here the square root is about 28.601). Historically, the sieve of Eratosthenes (dating from the Greek mathematics) implements this technique in a relatively efficient manner.

More modern techniques include the sieve of Atkin, probabilistic algorithms, and the cyclotomic AKS test.

Numbers near 818

Preceding numbers: …816, 817
Following numbers: 819, 820…

Nearest numbers from 818

Preceding prime number: 811
Following prime number: 821